Microchannel cooling in low material budget supports for silicon pixel detectors

Pixel detectors at future colliders will need to match very stringent requirement on position resolution. To ensure the needed mechanical stability and the removal of the power dissipated by the read-out electronic, the support structure and cooling add an important contribution to the total material in the active area, in terms of radiation length. We present the development, the construction and the mechanical–thermal characterization of prototypes of light material support for pixel detectors with microchannel for heat evacuation through forced convection of liquid coolant. The solution we choose shows several advantages: heat exchange is taking place efficiently due to the high ratio surface/volume and so high thermal conductivities can be obtained, minimally affecting the stiffness of the structure; the thermal resistances are reduced because of the contiguity between the fluid and the circuit dissipating power; the uniformity of temperature on the surface covered by of the sensors is also kept under control. Several prototypes implementing different geometries of micro-machined channels have been realized in composites materials (CFRP). FEA studies have been performed to validated the experimental test conducted in the thermo-fluid dynamic test bench we recently assembled in the INFN Pisa laboratory.